The writing process for the majority of Metallicaâs albums have followed the same process. A large slew of guitar riffs written primarily by James Hetfield, sometimes Kirk Hammett, and rarely the bandâs bass player, (that now being bass virtuoso Robert Trujillo) are reviewed and selected.
1 Delhi is most polluted city in the world in PM2.5 concentrations. 2  Half of the top 20 most polluted cities were in India, according to data.  PM2.5 is considered most harmful to health.
Follow @TIME. Ulan Bator, Mongoliaâthe second-most polluted city in the world. Credit: Doug Kanter / Bloomberg / Getty Images. Environmentalists here in the U.S. are not happy with President Obama, in part because he pulled back on a promise to tighten ground-level ozone and smog standards for air pollution.ir pollutionâboth indoor and outdoorâis a major health hazard. The WHO estimates that over 2 million people a year die prematurely from bad airâmost of them in poor countries and cities. Thatâs greater than the annual death toll from HIV/AIDS.